
<!DOCTYPE HTML>
<html lang="zh-hans" >
    <head>
        <meta charset="UTF-8">
        <meta content="text/html; charset=utf-8" http-equiv="Content-Type">
        <title>TypeScript 1.8 · TypeScript Handbook</title>
        <meta http-equiv="X-UA-Compatible" content="IE=edge" />
        <meta name="description" content="">
        <meta name="generator" content="GitBook 3.2.3">
        <meta name="author" content="Patrick Zhong">
        
        
    
    <link rel="stylesheet" href="../../gitbook/style.css">

    
            
                
                <link rel="stylesheet" href="../../gitbook/gitbook-plugin-highlight/website.css">
                
            
                
                <link rel="stylesheet" href="../../gitbook/gitbook-plugin-search/search.css">
                
            
                
                <link rel="stylesheet" href="../../gitbook/gitbook-plugin-fontsettings/website.css">
                
            
        

    

    
        
    
        
    
        
    
        
    
        
    
        
    

        
    
    
    <meta name="HandheldFriendly" content="true"/>
    <meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=no">
    <meta name="apple-mobile-web-app-capable" content="yes">
    <meta name="apple-mobile-web-app-status-bar-style" content="black">
    <link rel="apple-touch-icon-precomposed" sizes="152x152" href="../../gitbook/images/apple-touch-icon-precomposed-152.png">
    <link rel="shortcut icon" href="../../gitbook/images/favicon.ico" type="image/x-icon">

    
    <link rel="next" href="TypeScript 1.7.html" />
    
    
    <link rel="prev" href="TypeScript 2.0.html" />
    

    </head>
    <body>
        
<div class="book">
    <div class="book-summary">
        
            
<div id="book-search-input" role="search">
    <input type="text" placeholder="输入并搜索" />
</div>

            
                <nav role="navigation">
                


<ul class="summary">
    
    

    

    
        
        
    
        <li class="chapter " data-level="1.1" data-path="../../">
            
                <a href="../../">
            
                    
                    Introduction
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.2" data-path="../handbook/tutorials/">
            
                <a href="../handbook/tutorials/">
            
                    
                    快速上手
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.2.1" data-path="../handbook/tutorials/TypeScript in 5 minutes.html">
            
                <a href="../handbook/tutorials/TypeScript in 5 minutes.html">
            
                    
                    5分钟了解TypeScript
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.2.2" data-path="../handbook/tutorials/ASP.NET Core.html">
            
                <a href="../handbook/tutorials/ASP.NET Core.html">
            
                    
                    ASP.NET Core
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.2.3" data-path="../handbook/tutorials/ASP.NET 4.html">
            
                <a href="../handbook/tutorials/ASP.NET 4.html">
            
                    
                    ASP.NET 4
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.2.4" data-path="../handbook/tutorials/Gulp.html">
            
                <a href="../handbook/tutorials/Gulp.html">
            
                    
                    Gulp
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.2.5" data-path="../handbook/tutorials/Knockout.html">
            
                <a href="../handbook/tutorials/Knockout.html">
            
                    
                    Knockout.js
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.2.6" data-path="../handbook/tutorials/React & Webpack.html">
            
                <a href="../handbook/tutorials/React & Webpack.html">
            
                    
                    React与webpack
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.2.7" data-path="../handbook/tutorials/React.html">
            
                <a href="../handbook/tutorials/React.html">
            
                    
                    React
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.2.8" data-path="../handbook/tutorials/Angular 2.html">
            
                <a href="../handbook/tutorials/Angular 2.html">
            
                    
                    Angular 2
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.2.9" data-path="../handbook/tutorials/Migrating from JavaScript.html">
            
                <a href="../handbook/tutorials/Migrating from JavaScript.html">
            
                    
                    从JavaScript迁移到TypeScript
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.3" data-path="../handbook/">
            
                <a href="../handbook/">
            
                    
                    手册
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.3.1" data-path="../handbook/Basic Types.html">
            
                <a href="../handbook/Basic Types.html">
            
                    
                    基础类型
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.2" data-path="../handbook/Variable Declarations.html">
            
                <a href="../handbook/Variable Declarations.html">
            
                    
                    变量声明
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.3" data-path="../handbook/Interfaces.html">
            
                <a href="../handbook/Interfaces.html">
            
                    
                    接口
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.4" data-path="../handbook/Classes.html">
            
                <a href="../handbook/Classes.html">
            
                    
                    类
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.5" data-path="../handbook/Functions.html">
            
                <a href="../handbook/Functions.html">
            
                    
                    函数
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.6" data-path="../handbook/Generics.html">
            
                <a href="../handbook/Generics.html">
            
                    
                    泛型
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.7" data-path="../handbook/Enums.html">
            
                <a href="../handbook/Enums.html">
            
                    
                    枚举
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.8" data-path="../handbook/Type Inference.html">
            
                <a href="../handbook/Type Inference.html">
            
                    
                    类型推论
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.9" data-path="../handbook/Type Compatibility.html">
            
                <a href="../handbook/Type Compatibility.html">
            
                    
                    类型兼容性
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.10" data-path="../handbook/Advanced Types.html">
            
                <a href="../handbook/Advanced Types.html">
            
                    
                    高级类型
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.11" data-path="../handbook/Utilit Types.md">
            
                <span>
            
                    
                    实用工具类型
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.12" data-path="../handbook/Symbols.html">
            
                <a href="../handbook/Symbols.html">
            
                    
                    Symbols
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.13" data-path="../handbook/Iterators and Generators.html">
            
                <a href="../handbook/Iterators and Generators.html">
            
                    
                    Iterators 和 Generators
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.14" data-path="../handbook/Modules.html">
            
                <a href="../handbook/Modules.html">
            
                    
                    模块
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.15" data-path="../handbook/Namespaces.html">
            
                <a href="../handbook/Namespaces.html">
            
                    
                    命名空间
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.16" data-path="../handbook/Namespaces and Modules.html">
            
                <a href="../handbook/Namespaces and Modules.html">
            
                    
                    命名空间和模块
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.17" data-path="../handbook/Module Resolution.html">
            
                <a href="../handbook/Module Resolution.html">
            
                    
                    模块解析
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.18" data-path="../handbook/Declaration Merging.html">
            
                <a href="../handbook/Declaration Merging.html">
            
                    
                    声明合并
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.19" data-path="../handbook/Writing Definition Files.html">
            
                <a href="../handbook/Writing Definition Files.html">
            
                    
                    书写.d.ts文件
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.20" data-path="../handbook/JSX.html">
            
                <a href="../handbook/JSX.html">
            
                    
                    JSX
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.21" data-path="../handbook/Decorators.html">
            
                <a href="../handbook/Decorators.html">
            
                    
                    Decorators
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.22" data-path="../handbook/Mixins.html">
            
                <a href="../handbook/Mixins.html">
            
                    
                    混入
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.23" data-path="../handbook/Triple-Slash Directives.html">
            
                <a href="../handbook/Triple-Slash Directives.html">
            
                    
                    三斜线指令
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.3.24" data-path="../handbook/Type Checking JavaScript Files.html">
            
                <a href="../handbook/Type Checking JavaScript Files.html">
            
                    
                    JavaScript文件里的类型检查
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.4" data-path="../handbook/declaration files/Introduction.html">
            
                <a href="../handbook/declaration files/Introduction.html">
            
                    
                    如何书写声明文件
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.4.1" data-path="../handbook/declaration files/Library Structures.html">
            
                <a href="../handbook/declaration files/Library Structures.html">
            
                    
                    结构
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.4.2" data-path="../handbook/declaration files/Do's and Don'ts.html">
            
                <a href="../handbook/declaration files/Do's and Don'ts.html">
            
                    
                    规范
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.4.3" data-path="../handbook/declaration files/By Example.html">
            
                <a href="../handbook/declaration files/By Example.html">
            
                    
                    举例
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.4.4" data-path="../handbook/declaration files/Deep Dive.html">
            
                <a href="../handbook/declaration files/Deep Dive.html">
            
                    
                    深入
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.4.5" data-path="../handbook/declaration files/Publishing.html">
            
                <a href="../handbook/declaration files/Publishing.html">
            
                    
                    发布
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.4.6" data-path="../handbook/declaration files/Consumption.html">
            
                <a href="../handbook/declaration files/Consumption.html">
            
                    
                    使用
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.5" data-path="../handbook/tsconfig.json.html">
            
                <a href="../handbook/tsconfig.json.html">
            
                    
                    工程配置
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.5.1" data-path="../handbook/tsconfig.json.html">
            
                <a href="../handbook/tsconfig.json.html">
            
                    
                    tsconfig.json
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.5.2" data-path="../handbook/Project References.html">
            
                <a href="../handbook/Project References.html">
            
                    
                    工程引用
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.5.3" data-path="../handbook/Typings for NPM Packages.html">
            
                <a href="../handbook/Typings for NPM Packages.html">
            
                    
                    NPM包的类型
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.5.4" data-path="../handbook/Compiler Options.html">
            
                <a href="../handbook/Compiler Options.html">
            
                    
                    编译选项
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.5.5" data-path="../handbook/Configuring Watch.html">
            
                <a href="../handbook/Configuring Watch.html">
            
                    
                    配置 Watch
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.5.6" data-path="../handbook/Compiler Options in MSBuild.html">
            
                <a href="../handbook/Compiler Options in MSBuild.html">
            
                    
                    在MSBuild里使用编译选项
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.5.7" data-path="../handbook/Integrating with Build Tools.html">
            
                <a href="../handbook/Integrating with Build Tools.html">
            
                    
                    与其它构建工具整合
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.5.8" data-path="../handbook/Nightly Builds.html">
            
                <a href="../handbook/Nightly Builds.html">
            
                    
                    使用TypeScript的每日构建版本
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.6" data-path="../wiki/">
            
                <a href="../wiki/">
            
                    
                    Wiki
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.6.1" data-path="../wiki/this-in-TypeScript.html">
            
                <a href="../wiki/this-in-TypeScript.html">
            
                    
                    TypeScript里的this
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.6.2" data-path="../wiki/coding_guidelines.html">
            
                <a href="../wiki/coding_guidelines.html">
            
                    
                    编码规范
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.6.3" data-path="../wiki/Common Errors.html">
            
                <a href="../wiki/Common Errors.html">
            
                    
                    常见编译错误
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.6.4" data-path="../wiki/TypeScript-Editor-Support.html">
            
                <a href="../wiki/TypeScript-Editor-Support.html">
            
                    
                    支持TypeScript的编辑器
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.6.5" data-path="../wiki/Using-TypeScript-With-ASP.NET-5.html">
            
                <a href="../wiki/Using-TypeScript-With-ASP.NET-5.html">
            
                    
                    结合ASP.NET v5使用TypeScript
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.6.6" data-path="../wiki/Architectural-Overview.html">
            
                <a href="../wiki/Architectural-Overview.html">
            
                    
                    架构概述
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.6.7" data-path="../wiki/Roadmap.html">
            
                <a href="../wiki/Roadmap.html">
            
                    
                    发展路线图
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.7" data-path="../release-notes/">
            
                <a href="../release-notes/">
            
                    
                    新增功能
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.7.1" data-path="../release-notes/TypeScript 3.1.html">
            
                <a href="../release-notes/TypeScript 3.1.html">
            
                    
                    TypeScript 3.1
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.2" data-path="../release-notes/TypeScript 3.0.html">
            
                <a href="../release-notes/TypeScript 3.0.html">
            
                    
                    TypeScript 3.0
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.3" data-path="../release-notes/TypeScript 2.9.html">
            
                <a href="../release-notes/TypeScript 2.9.html">
            
                    
                    TypeScript 2.9
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.4" data-path="../release-notes/TypeScript 2.8.html">
            
                <a href="../release-notes/TypeScript 2.8.html">
            
                    
                    TypeScript 2.8
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.5" data-path="../release-notes/TypeScript 2.7.html">
            
                <a href="../release-notes/TypeScript 2.7.html">
            
                    
                    TypeScript 2.7
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.6" data-path="../release-notes/TypeScript 2.6.html">
            
                <a href="../release-notes/TypeScript 2.6.html">
            
                    
                    TypeScript 2.6
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.7" data-path="../release-notes/TypeScript 2.5.html">
            
                <a href="../release-notes/TypeScript 2.5.html">
            
                    
                    TypeScript 2.5
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.8" data-path="../release-notes/TypeScript 2.4.html">
            
                <a href="../release-notes/TypeScript 2.4.html">
            
                    
                    TypeScript 2.4
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.9" data-path="../release-notes/TypeScript 2.3.html">
            
                <a href="../release-notes/TypeScript 2.3.html">
            
                    
                    TypeScript 2.3
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.10" data-path="../release-notes/TypeScript 2.2.html">
            
                <a href="../release-notes/TypeScript 2.2.html">
            
                    
                    TypeScript 2.2
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.11" data-path="../release-notes/TypeScript 2.1.html">
            
                <a href="../release-notes/TypeScript 2.1.html">
            
                    
                    TypeScript 2.1
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.12" data-path="../release-notes/TypeScript 2.0.html">
            
                <a href="../release-notes/TypeScript 2.0.html">
            
                    
                    TypeScript 2.0
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.13" data-path="../release-notes/TypeScript 1.8.html">
            
                <a href="../release-notes/TypeScript 1.8.html">
            
                    
                    TypeScript 1.8
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.14" data-path="../release-notes/TypeScript 1.7.html">
            
                <a href="../release-notes/TypeScript 1.7.html">
            
                    
                    TypeScript 1.7
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.15" data-path="../release-notes/TypeScript 1.6.html">
            
                <a href="../release-notes/TypeScript 1.6.html">
            
                    
                    TypeScript 1.6
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.16" data-path="../release-notes/TypeScript 1.5.html">
            
                <a href="../release-notes/TypeScript 1.5.html">
            
                    
                    TypeScript 1.5
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.17" data-path="../release-notes/TypeScript 1.4.html">
            
                <a href="../release-notes/TypeScript 1.4.html">
            
                    
                    TypeScript 1.4
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.18" data-path="../release-notes/TypeScript 1.3.html">
            
                <a href="../release-notes/TypeScript 1.3.html">
            
                    
                    TypeScript 1.3
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.7.19" data-path="../release-notes/TypeScript 1.1.html">
            
                <a href="../release-notes/TypeScript 1.1.html">
            
                    
                    TypeScript 1.1
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.8" data-path="breaking-changes.html">
            
                <a href="breaking-changes.html">
            
                    
                    Breaking Changes
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.8.1" data-path="TypeScript 2.4.html">
            
                <a href="TypeScript 2.4.html">
            
                    
                    TypeScript 2.4
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.8.2" data-path="TypeScript 2.3.html">
            
                <a href="TypeScript 2.3.html">
            
                    
                    TypeScript 2.3
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.8.3" data-path="TypeScript 2.2.html">
            
                <a href="TypeScript 2.2.html">
            
                    
                    TypeScript 2.2
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.8.4" data-path="TypeScript 2.1.html">
            
                <a href="TypeScript 2.1.html">
            
                    
                    TypeScript 2.1
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.8.5" data-path="TypeScript 2.0.html">
            
                <a href="TypeScript 2.0.html">
            
                    
                    TypeScript 2.0
            
                </a>
            

            
        </li>
    
        <li class="chapter active" data-level="1.8.6" data-path="TypeScript 1.8.html">
            
                <a href="TypeScript 1.8.html">
            
                    
                    TypeScript 1.8
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.8.7" data-path="TypeScript 1.7.html">
            
                <a href="TypeScript 1.7.html">
            
                    
                    TypeScript 1.7
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.8.8" data-path="TypeScript 1.6.html">
            
                <a href="TypeScript 1.6.html">
            
                    
                    TypeScript 1.6
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.8.9" data-path="TypeScript 1.5.html">
            
                <a href="TypeScript 1.5.html">
            
                    
                    TypeScript 1.5
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.8.10" data-path="TypeScript 1.4.html">
            
                <a href="TypeScript 1.4.html">
            
                    
                    TypeScript 1.4
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    

    

    <li class="divider"></li>

    <li>
        <a href="https://www.gitbook.com" target="blank" class="gitbook-link">
            本书使用 GitBook 发布
        </a>
    </li>
</ul>


                </nav>
            
        
    </div>

    <div class="book-body">
        
            <div class="body-inner">
                
                    

<div class="book-header" role="navigation">
    

    <!-- Title -->
    <h1>
        <i class="fa fa-circle-o-notch fa-spin"></i>
        <a href="../.." >TypeScript 1.8</a>
    </h1>
</div>




                    <div class="page-wrapper" tabindex="-1" role="main">
                        <div class="page-inner">
                            
<div id="book-search-results">
    <div class="search-noresults">
    
                                <section class="normal markdown-section">
                                
                                <h1 id="typescript-18">TypeScript 1.8</h1>
<p>&#x5B8C;&#x6574;&#x7684;&#x7834;&#x574F;&#x6027;&#x6539;&#x52A8;&#x5217;&#x8868;&#x8BF7;&#x5230;&#x8FD9;&#x91CC;&#x67E5;&#x770B;:<a href="https://github.com/Microsoft/TypeScript/issues?q=is%3Aissue+milestone%3A%22TypeScript+1.8%22+label%3A%22Breaking+Change%22+is%3Aclosed" target="_blank">breaking change issues</a>&#x3002;</p>
<h4 id="&#x73B0;&#x5728;&#x751F;&#x6210;&#x6A21;&#x5757;&#x4EE3;&#x7801;&#x65F6;&#x4F1A;&#x5E26;&#x6709;use-strict&#x5934;">&#x73B0;&#x5728;&#x751F;&#x6210;&#x6A21;&#x5757;&#x4EE3;&#x7801;&#x65F6;&#x4F1A;&#x5E26;&#x6709;<code>&quot;use strict&quot;;</code>&#x5934;</h4>
<p>&#x5728;ES6&#x6A21;&#x5F0F;&#x4E0B;&#x6A21;&#x5757;&#x603B;&#x662F;&#x5728;&#x4E25;&#x683C;&#x6A21;&#x5F0F;&#x4E0B;&#x89E3;&#x6790;&#xFF0C;&#x5BF9;&#x4E8E;&#x751F;&#x6210;&#x76EE;&#x6807;&#x4E3A;&#x975E;ES6&#x7684;&#x5374;&#x4E0D;&#x662F;&#x8FD9;&#x6837;&#x3002;&#x4ECE;TypeScript 1.8&#x5F00;&#x59CB;&#xFF0C;&#x751F;&#x6210;&#x7684;&#x6A21;&#x5757;&#x5C06;&#x603B;&#x4E3A;&#x4E25;&#x683C;&#x6A21;&#x5F0F;&#x3002;&#x8FD9;&#x5E94;&#x8BE5;&#x4E0D;&#x4F1A;&#x5BF9;&#x73B0;&#x6709;&#x7684;&#x5927;&#x90E8;&#x5206;&#x4EE3;&#x7801;&#x4EA7;&#x751F;&#x5F71;&#x54CD;&#xFF0C;&#x56E0;&#x4E3A;TypeScript&#x628A;&#x5927;&#x591A;&#x6570;&#x56E0;&#x4E3A;&#x4E25;&#x683C;&#x6A21;&#x5F0F;&#x800C;&#x4EA7;&#x751F;&#x7684;&#x9519;&#x8BEF;&#x5F53;&#x505A;&#x7F16;&#x8BD1;&#x65F6;&#x9519;&#x8BEF;&#xFF0C;&#x4F46;&#x8FD8;&#x662F;&#x6709;&#x4E00;&#x4E9B;&#x5728;&#x8FD0;&#x884C;&#x65F6;&#x624D;&#x53D1;&#x751F;&#x9519;&#x8BEF;&#x7684;TypeScript&#x4EE3;&#x7801;&#xFF0C;&#x6BD4;&#x5982;&#x8D4B;&#x503C;&#x7ED9;<code>NaN</code>&#xFF0C;&#x73B0;&#x5728;&#x5C06;&#x4F1A;&#x76F4;&#x63A5;&#x62A5;&#x9519;&#x3002;&#x4F60;&#x53EF;&#x4EE5;&#x53C2;&#x8003;<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode" target="_blank">MDN Article</a>&#x5B66;&#x4E60;&#x5173;&#x4E8E;&#x4E25;&#x683C;&#x6A21;&#x5F0F;&#x4E0E;&#x975E;&#x4E25;&#x683C;&#x6A21;&#x5F0F;&#x7684;&#x533A;&#x522B;&#x3002;</p>
<p>&#x82E5;&#x60F3;&#x7981;&#x7528;&#x8FD9;&#x4E2A;&#x884C;&#x4E3A;&#xFF0C;&#x5728;&#x547D;&#x4EE4;&#x884C;&#x91CC;&#x4F20;<code>--noImplicitUseStrict</code>&#x9009;&#x9879;&#x6216;&#x5728;tsconfig.json&#x6587;&#x4EF6;&#x91CC;&#x6307;&#x5B9A;&#x3002;</p>
<h4 id="&#x4ECE;&#x6A21;&#x5757;&#x91CC;&#x5BFC;&#x51FA;&#x975E;&#x5C40;&#x90E8;&#x540D;&#x79F0;">&#x4ECE;&#x6A21;&#x5757;&#x91CC;&#x5BFC;&#x51FA;&#x975E;&#x5C40;&#x90E8;&#x540D;&#x79F0;</h4>
<p>&#x4F9D;&#x636E;ES6/ES2015&#x89C4;&#x8303;&#xFF0C;&#x4ECE;&#x6A21;&#x5757;&#x91CC;&#x5BFC;&#x51FA;&#x975E;&#x5C40;&#x90E8;&#x540D;&#x79F0;&#x5C06;&#x4F1A;&#x62A5;&#x9519;&#x3002;</p>
<p><strong>&#x4F8B;&#x5B50;</strong></p>
<pre><code class="lang-ts"><span class="hljs-keyword">export</span> { Promise }; <span class="hljs-comment">// Error</span>
</code></pre>
<p><strong>&#x63A8;&#x8350;</strong></p>
<p>&#x5728;&#x5BFC;&#x51FA;&#x4E4B;&#x524D;&#xFF0C;&#x4F7F;&#x7528;&#x5C40;&#x90E8;&#x53D8;&#x91CF;&#x58F0;&#x660E;&#x6355;&#x83B7;&#x90A3;&#x4E2A;&#x5168;&#x5C40;&#x540D;&#x79F0;&#x3002;</p>
<pre><code class="lang-ts"><span class="hljs-keyword">const</span> localPromise = Promise;
<span class="hljs-keyword">export</span> { localPromise as Promise };
</code></pre>
<h4 id="&#x9ED8;&#x8BA4;&#x542F;&#x7528;&#x4EE3;&#x7801;&#x53EF;&#x8FBE;&#x6027;&#xFF08;reachability&#xFF09;&#x68C0;&#x67E5;">&#x9ED8;&#x8BA4;&#x542F;&#x7528;&#x4EE3;&#x7801;&#x53EF;&#x8FBE;&#x6027;&#xFF08;Reachability&#xFF09;&#x68C0;&#x67E5;</h4>
<p>TypeScript 1.8&#x91CC;&#xFF0C;&#x6211;&#x4EEC;&#x6DFB;&#x52A0;&#x4E86;&#x4E00;&#x4E9B;<a href="https://github.com/Microsoft/TypeScript/pull/4788" target="_blank">&#x53EF;&#x8FBE;&#x6027;&#x68C0;&#x67E5;</a>&#x6765;&#x963B;&#x6B62;&#x4E00;&#x4E9B;&#x79CD;&#x7C7B;&#x7684;&#x9519;&#x8BEF;&#x3002;&#x7279;&#x522B;&#x662F;&#xFF1A;</p>
<ol>
<li><p>&#x68C0;&#x67E5;&#x4EE3;&#x7801;&#x7684;&#x53EF;&#x8FBE;&#x6027;&#xFF08;&#x9ED8;&#x8BA4;&#x542F;&#x7528;&#xFF0C;&#x53EF;&#x4EE5;&#x901A;&#x8FC7;<code>allowUnreachableCode</code>&#x7F16;&#x8BD1;&#x5668;&#x9009;&#x9879;&#x7981;&#x7528;&#xFF09;</p>
<pre><code class="lang-ts">   <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">test1</span>(<span class="hljs-params"></span>) </span>{
       <span class="hljs-keyword">return</span> <span class="hljs-number">1</span>;
       <span class="hljs-keyword">return</span> <span class="hljs-number">2</span>; <span class="hljs-comment">// error here</span>
   }

   <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">test2</span>(<span class="hljs-params">x</span>) </span>{
       <span class="hljs-keyword">if</span> (x) {
           <span class="hljs-keyword">return</span> <span class="hljs-number">1</span>;
       }
       <span class="hljs-keyword">else</span> {
           <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-built_in">Error</span>(<span class="hljs-string">&quot;NYI&quot;</span>)
       }
       <span class="hljs-keyword">var</span> y = <span class="hljs-number">1</span>; <span class="hljs-comment">// error here</span>
   }
</code></pre>
</li>
<li><p>&#x68C0;&#x67E5;&#x6807;&#x7B7E;&#x662F;&#x5426;&#x88AB;&#x4F7F;&#x7528;&#xFF08;&#x9ED8;&#x8BA4;&#x542F;&#x7528;&#xFF0C;&#x53EF;&#x4EE5;&#x901A;&#x8FC7;<code>allowUnusedLabels</code>&#x7F16;&#x8BD1;&#x5668;&#x9009;&#x9879;&#x7981;&#x7528;&#xFF09;</p>
<pre><code class="lang-ts">l: <span class="hljs-comment">// error will be reported - label `l` is unused</span>
<span class="hljs-keyword">while</span> (<span class="hljs-literal">true</span>) {
}

(x) =&gt; { x:x } <span class="hljs-comment">// error will be reported - label `x` is unused</span>
</code></pre>
</li>
<li><p>&#x68C0;&#x67E5;&#x662F;&#x5426;&#x51FD;&#x6570;&#x91CC;&#x6240;&#x6709;&#x5E26;&#x6709;&#x8FD4;&#x56DE;&#x503C;&#x7C7B;&#x578B;&#x6CE8;&#x89E3;&#x7684;&#x4EE3;&#x7801;&#x8DEF;&#x5F84;&#x90FD;&#x8FD4;&#x56DE;&#x4E86;&#x503C;&#xFF08;&#x9ED8;&#x8BA4;&#x542F;&#x7528;&#xFF0C;&#x53EF;&#x4EE5;&#x901A;&#x8FC7;<code>noImplicitReturns</code>&#x7F16;&#x8BD1;&#x5668;&#x9009;&#x9879;&#x7981;&#x7528;&#xFF09;</p>
<pre><code class="lang-ts"><span class="hljs-comment">// error will be reported since function does not return anything explicitly when `x` is falsy.</span>
<span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">test</span>(<span class="hljs-params">x</span>): <span class="hljs-title">number</span> </span>{
   <span class="hljs-keyword">if</span> (x) <span class="hljs-keyword">return</span> <span class="hljs-number">10</span>;
}
</code></pre>
</li>
<li><p>&#x68C0;&#x67E5;&#x63A7;&#x5236;&#x6D41;&#x662F;&#x5426;&#x80FD;&#x8FDB;&#x5230;switch&#x8BED;&#x53E5;&#x7684;case&#x91CC;&#xFF08;&#x9ED8;&#x8BA4;&#x7981;&#x7528;&#xFF0C;&#x53EF;&#x4EE5;&#x901A;&#x8FC7;<code>noFallthroughCasesInSwitch</code>&#x7F16;&#x8BD1;&#x5668;&#x9009;&#x9879;&#x542F;&#x7528;&#xFF09;&#x3002;&#x6CE8;&#x610F;&#x6CA1;&#x6709;&#x8BED;&#x53E5;&#x7684;case&#x4E0D;&#x4F1A;&#x88AB;&#x68C0;&#x67E5;&#x3002;</p>
<pre><code class="lang-ts"><span class="hljs-keyword">switch</span>(x) {
   <span class="hljs-comment">// OK</span>
   <span class="hljs-keyword">case</span> <span class="hljs-number">1</span>:
   <span class="hljs-keyword">case</span> <span class="hljs-number">2</span>:
       <span class="hljs-keyword">return</span> <span class="hljs-number">1</span>;
}
<span class="hljs-keyword">switch</span>(x) {
   <span class="hljs-keyword">case</span> <span class="hljs-number">1</span>:
       <span class="hljs-keyword">if</span> (y) <span class="hljs-keyword">return</span> <span class="hljs-number">1</span>;
   <span class="hljs-keyword">case</span> <span class="hljs-number">2</span>:
       <span class="hljs-keyword">return</span> <span class="hljs-number">2</span>;
}
</code></pre>
</li>
</ol>
<p>&#x5982;&#x679C;&#x4F60;&#x770B;&#x5230;&#x4E86;&#x8FD9;&#x4E9B;&#x9519;&#x8BEF;&#xFF0C;&#x4F46;&#x662F;&#x4F60;&#x8BA4;&#x4E3A;&#x8FD9;&#x65F6;&#x7684;&#x4EE3;&#x7801;&#x662F;&#x5408;&#x7406;&#x7684;&#x8BDD;&#xFF0C;&#x4F60;&#x53EF;&#x4EE5;&#x901A;&#x8FC7;&#x7F16;&#x8BD1;&#x9009;&#x9879;&#x6765;&#x963B;&#x6B62;&#x62A5;&#x9519;&#x3002;</p>
<h4 id="-module&#x4E0D;&#x5141;&#x8BB8;&#x4E0E;--outfile&#x4E00;&#x8D77;&#x51FA;&#x73B0;&#xFF0C;&#x9664;&#x975E;---module&#x88AB;&#x6307;&#x5B9A;&#x4E3A;amd&#x6216;system"><code>--module</code>&#x4E0D;&#x5141;&#x8BB8;&#x4E0E;<code>--outFile</code>&#x4E00;&#x8D77;&#x51FA;&#x73B0;&#xFF0C;&#x9664;&#x975E; <code>--module</code>&#x88AB;&#x6307;&#x5B9A;&#x4E3A;<code>amd</code>&#x6216;<code>system</code></h4>
<p>&#x4E4B;&#x524D;&#x4F7F;&#x7528;&#x6A21;&#x5757;&#x6307;&#x5B9A;&#x8FD9;&#x4E24;&#x4E2A;&#x7684;&#x65F6;&#x5019;&#xFF0C;&#x4F1A;&#x751F;&#x6210;&#x7A7A;&#x7684;<code>out</code>&#x6587;&#x4EF6;&#x4E14;&#x4E0D;&#x4F1A;&#x62A5;&#x9519;&#x3002;</p>
<h4 id="&#x6807;&#x51C6;&#x5E93;&#x91CC;&#x7684;dom-api&#x53D8;&#x52A8;">&#x6807;&#x51C6;&#x5E93;&#x91CC;&#x7684;DOM API&#x53D8;&#x52A8;</h4>
<ul>
<li><strong>ImageData.data</strong>&#x73B0;&#x5728;&#x7684;&#x7C7B;&#x578B;&#x4E3A;<code>Uint8ClampedArray</code>&#x800C;&#x4E0D;&#x662F;<code>number[]</code>&#x3002;&#x67E5;&#x770B;<a href="https://github.com/Microsoft/TypeScript/issues/949" target="_blank">#949</a>&#x3002;</li>
<li><strong>HTMLSelectElement .options</strong>&#x73B0;&#x5728;&#x7684;&#x7C7B;&#x578B;&#x4E3A;<code>HTMLCollection</code>&#x800C;&#x4E0D;&#x662F;<code>HTMLSelectElement</code>&#x3002;&#x67E5;&#x770B;<a href="https://github.com/Microsoft/TypeScript/issues/1558" target="_blank">#1558</a>&#x3002;</li>
<li><strong>HTMLTableElement.createCaption</strong>&#xFF0C;<strong>HTMLTableElement.createTBody</strong>&#xFF0C;<strong>HTMLTableElement.createTFoot</strong>&#xFF0C;<strong>HTMLTableElement.createTHead</strong>&#xFF0C;<strong>HTMLTableElement.insertRow</strong>&#xFF0C;<strong>HTMLTableSectionElement.insertRow</strong>&#x548C;<strong>HTMLTableElement.insertRow</strong>&#x73B0;&#x5728;&#x8FD4;&#x56DE;<code>HTMLTableRowElement</code>&#x800C;&#x4E0D;&#x662F;<code>HTMLElement</code>&#x3002;&#x67E5;&#x770B;<a href="https://github.com/Microsoft/TypeScript/issues/3583" target="_blank">#3583</a>&#x3002;</li>
<li><strong>HTMLTableRowElement.insertCell</strong>&#x73B0;&#x5728;&#x8FD4;&#x56DE;<code>HTMLTableCellElement</code>&#x800C;&#x4E0D;&#x662F;<code>HTMLElement</code>&#x67E5;&#x770B;<a href="https://github.com/Microsoft/TypeScript/issues/3583" target="_blank">#3583</a>&#x3002;</li>
<li><strong>IDBObjectStore.createIndex</strong>&#x548C;<strong>IDBDatabase.createIndex</strong>&#x7B2C;&#x4E8C;&#x4E2A;&#x53C2;&#x6570;&#x7C7B;&#x578B;&#x4E3A;<code>IDBObjectStoreParameters</code>&#x800C;&#x4E0D;&#x662F;<code>any</code>&#x3002;&#x67E5;&#x770B;<a href="https://github.com/Microsoft/TypeScript/issues/5932" target="_blank">#5932</a>&#x3002;</li>
<li><strong>DataTransferItemList.Item</strong>&#x8FD4;&#x56DE;&#x503C;&#x7C7B;&#x578B;&#x53D8;&#x4E3A;<code>DataTransferItem</code>&#x800C;&#x4E0D;&#x662F;<code>File</code>&#x3002;&#x67E5;&#x770B;<a href="https://github.com/Microsoft/TypeScript/issues/6106" target="_blank">#6106</a>&#x3002;</li>
<li><strong>Window.open</strong>&#x8FD4;&#x56DE;&#x503C;&#x7C7B;&#x578B;&#x53D8;&#x4E3A;<code>Window</code>&#x800C;&#x4E0D;&#x662F;<code>any</code>&#x3002;&#x67E5;&#x770B;<a href="https://github.com/Microsoft/TypeScript/issues/6418" target="_blank">#6418</a>&#x3002;</li>
<li><strong>WeakMap.clear</strong>&#x88AB;&#x79FB;&#x9664;&#x3002;&#x67E5;&#x770B;<a href="https://github.com/Microsoft/TypeScript/issues/6500" target="_blank">#6500</a>&#x3002;</li>
</ul>
<h4 id="&#x5728;super-call&#x4E4B;&#x524D;&#x4E0D;&#x5141;&#x8BB8;&#x4F7F;&#x7528;this">&#x5728;super-call&#x4E4B;&#x524D;&#x4E0D;&#x5141;&#x8BB8;&#x4F7F;&#x7528;<code>this</code></h4>
<p>ES6&#x4E0D;&#x5141;&#x8BB8;&#x5728;&#x6784;&#x9020;&#x51FD;&#x6570;&#x58F0;&#x660E;&#x91CC;&#x8BBF;&#x95EE;<code>this</code>&#x3002;</p>
<p>&#x6BD4;&#x5982;&#xFF1A;</p>
<pre><code class="lang-typescript"><span class="hljs-keyword">class</span> B {
    <span class="hljs-keyword">constructor</span>(that?: any) {}
}

<span class="hljs-keyword">class</span> C extends B {
    <span class="hljs-keyword">constructor</span>() {
        <span class="hljs-keyword">super</span>(<span class="hljs-keyword">this</span>);  <span class="hljs-comment">// error;</span>
    }
}

<span class="hljs-keyword">class</span> D extends B {
    <span class="hljs-keyword">private</span> _prop1: <span class="hljs-built_in">number</span>;
    <span class="hljs-keyword">constructor</span>() {
        <span class="hljs-keyword">this</span>._prop1 = <span class="hljs-number">10</span>;  <span class="hljs-comment">// error</span>
        <span class="hljs-keyword">super</span>();
    }
}
</code></pre>

                                
                                </section>
                            
    </div>
    <div class="search-results">
        <div class="has-results">
            
            <h1 class="search-results-title"><span class='search-results-count'></span> results matching "<span class='search-query'></span>"</h1>
            <ul class="search-results-list"></ul>
            
        </div>
        <div class="no-results">
            
            <h1 class="search-results-title">No results matching "<span class='search-query'></span>"</h1>
            
        </div>
    </div>
</div>

                        </div>
                    </div>
                
            </div>

            
                
                <a href="TypeScript 2.0.html" class="navigation navigation-prev " aria-label="Previous page: TypeScript 2.0">
                    <i class="fa fa-angle-left"></i>
                </a>
                
                
                <a href="TypeScript 1.7.html" class="navigation navigation-next " aria-label="Next page: TypeScript 1.7">
                    <i class="fa fa-angle-right"></i>
                </a>
                
            
        
    </div>

    <script>
        var gitbook = gitbook || [];
        gitbook.push(function() {
            gitbook.page.hasChanged({"page":{"title":"TypeScript 1.8","level":"1.8.6","depth":2,"next":{"title":"TypeScript 1.7","level":"1.8.7","depth":2,"path":"doc/breaking-changes/TypeScript 1.7.md","ref":"./doc/breaking-changes/TypeScript 1.7.md","articles":[]},"previous":{"title":"TypeScript 2.0","level":"1.8.5","depth":2,"path":"doc/breaking-changes/TypeScript 2.0.md","ref":"./doc/breaking-changes/TypeScript 2.0.md","articles":[]},"dir":"ltr"},"config":{"plugins":[],"styles":{"website":"styles/website.css","pdf":"styles/pdf.css","epub":"styles/epub.css","mobi":"styles/mobi.css","ebook":"styles/ebook.css","print":"styles/print.css"},"pluginsConfig":{"highlight":{},"search":{},"lunr":{"maxIndexSize":1000000,"ignoreSpecialCharacters":false},"sharing":{"facebook":true,"twitter":true,"google":false,"weibo":false,"instapaper":false,"vk":false,"all":["facebook","google","twitter","weibo","instapaper"]},"fontsettings":{"theme":"white","family":"sans","size":2},"theme-default":{"styles":{"website":"styles/website.css","pdf":"styles/pdf.css","epub":"styles/epub.css","mobi":"styles/mobi.css","ebook":"styles/ebook.css","print":"styles/print.css"},"showLevel":false}},"theme":"default","author":"Patrick Zhong","pdf":{"pageNumbers":true,"fontSize":12,"fontFamily":"Arial","paperSize":"a4","chapterMark":"pagebreak","pageBreaksBefore":"/","margin":{"right":62,"left":62,"top":56,"bottom":56}},"structure":{"langs":"LANGS.md","readme":"preface.md","glossary":"GLOSSARY.md","summary":"SUMMARY.md"},"variables":{},"title":"TypeScript Handbook","language":"zh-hans","gitbook":">3.0.0","description":"Translation of official TypeScript Handbook"},"file":{"path":"doc/breaking-changes/TypeScript 1.8.md","mtime":"2018-10-13T09:48:54.000Z","type":"markdown"},"gitbook":{"version":"3.2.3","time":"2018-10-13T09:57:42.904Z"},"basePath":"../..","book":{"language":""}});
        });
    </script>
</div>

        
    <script src="../../gitbook/gitbook.js"></script>
    <script src="../../gitbook/theme.js"></script>
    
        
        <script src="../../gitbook/gitbook-plugin-search/search-engine.js"></script>
        
    
        
        <script src="../../gitbook/gitbook-plugin-search/search.js"></script>
        
    
        
        <script src="../../gitbook/gitbook-plugin-lunr/lunr.min.js"></script>
        
    
        
        <script src="../../gitbook/gitbook-plugin-lunr/search-lunr.js"></script>
        
    
        
        <script src="../../gitbook/gitbook-plugin-sharing/buttons.js"></script>
        
    
        
        <script src="../../gitbook/gitbook-plugin-fontsettings/fontsettings.js"></script>
        
    

    </body>
</html>

